Unlocking my Galaxy S4 doesn't work

yesterday I got my ncfring. I have installed and configured the apps on my Samsung Galaxy S4 and registered the ring.
The ring was detected and facebook call works. When trying to unlock the phone using NFC Ring Unlock, I can here the pling and the plong sound, but the app doesn't unock. only the manual unlock using pin or mail and password unlocks the phone. What did I wrong or forget?
Unfortunately the manual doesn't really help. I looked for a video tutorial, which helped me, setting up the apps.